Influence of Gd3+ co-doping on structural property of CaMoO4:Eu nanoparticles

A facile auto-combustion route is used for the synthesis of Gd3+ (2, 5, 7 and 10 at%) co-doped CaMoO4:Eu nanoparticles. X-ray diffraction study suggests that as-prepared samples have extra impurity phases in addition to main tetragonal phase of CaMoO4, and such extra phases decrease as the annealing temperature increases from 600 to 900 degrees C. The crystal structure has been analysed using Rietveld program. It has space group I4(1)/a (88) and Z = 4 (number of CaMoO4 formula units per unit cell). Average crystallite sizes of as-prepared, 600 and 900 degrees C annealed samples for 2 at% Gd3+ are found to be similar to 33, 48 and 61 nm, respectively. The lattice strains of 5 at% Gd3+ co-doped CaMoO4:Eu for as-prepared and 900 degrees C are 0.001 and 0.002, respectively. Fourier transform infrared spectroscopy gives the absorption bands at similar to 815 and 427 cm(-1), which are related to asymmetric stretching and bending vibrations of MoO42- tetrahedron. Particle morphology is studied using scanning and transmission electron microscopy (SEM and TEM), and aggregation of particles is found. X-ray photoelectron spectroscopy (XPS) is utilized to examine the oxidation states of metal ions/oxygen and oxygen ion vacancies in Gd3+ co-doped CaMoO4:Eu. With an increase in Gd3+ concentration, peaks corresponding to the Gd3+ (2p(3/2) and 2p(5/2)) binding energy could be detected.